├── .gitignore ├── cache.go ├── README.md ├── memcache.go ├── memcache_test.go └── LICENSE /.gitignore: -------------------------------------------------------------------------------- 1 | # Compiled Object files, Static and Dynamic libs (Shared Objects) 2 | *.o 3 | *.a 4 | *.so 5 | 6 | # Folders 7 | _obj 8 | _test 9 | 10 | # Architecture specific extensions/prefixes 11 | *.[568vq] 12 | [568vq].out 13 | 14 | *.cgo1.go 15 | *.cgo2.c 16 | _cgo_defun.c 17 | _cgo_gotypes.go 18 | _cgo_export.* 19 | 20 | _testmain.go 21 | 22 | *.exe 23 | *.test 24 | *.prof 25 | -------------------------------------------------------------------------------- /cache.go: -------------------------------------------------------------------------------- 1 | package cache 2 | 3 | 4 | 5 | //return status of chache 6 | type CacheStatus struct { 7 | Gets int64 8 | Hits int64 9 | MaxItemSize int 10 | CurrentSize int 11 | } 12 | 13 | //this is a interface which defines some common functions 14 | type Cache interface{ 15 | Set(key string, value interface{}) 16 | Get(key string) (interface{}, bool) 17 | Delete(key string) 18 | Status()(*CacheStatus) 19 | } -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # cache 2 | A golang memcache with LRU to swap 3 | 4 | Install 5 | === 6 | 7 | go get github.com/g4zhuj/cache 8 | 9 | Usage 10 | === 11 | 12 | 13 | ### init 14 | 15 | ``` 16 | // If maxItemSize is zero, the cache has no limit. 17 | var cache Cache 18 | maxSize = 1024 19 | cache = NewMemCache(maxSize) 20 | ``` 21 | 22 | ### Get 23 | 24 | ``` 25 | value, ok := cache.Get("key") 26 | ``` 27 | 28 | ### Set 29 | 30 | ``` 31 | cache.Set("key", "value") 32 | ``` 33 | 34 | ### Delete 35 | 36 | ``` 37 | cache.Delete("delKey") 38 | ``` 39 | 40 | 41 | ### Status 42 | 43 | ``` 44 | status := cache.Status() 45 | fmt.Println("Gets Count: ", status.Gets) 46 | fmt.Println("Hits Count: ", status.Hits) 47 | fmt.Println("MaxItemSize: ", status.MaxItemSize) 48 | fmt.Println("CurrentSize: ", status.CurrentSize) 49 | ``` 50 | 51 | 52 | 53 | -------------------------------------------------------------------------------- /memcache.go: -------------------------------------------------------------------------------- 1 | package cache 2 | 3 | import ( 4 | "container/list" 5 | "sync" 6 | "sync/atomic" 7 | //"fmt" 8 | ) 9 | 10 | // An AtomicInt is an int64 to be accessed atomically. 11 | type AtomicInt int64 12 | 13 | // MemCache is an LRU cache. It is safe for concurrent access. 14 | type MemCache struct { 15 | mutex sync.RWMutex 16 | maxItemSize int 17 | cacheList *list.List 18 | cache map[interface{}]*list.Element 19 | hits, gets AtomicInt 20 | } 21 | 22 | type entry struct { 23 | key interface{} 24 | value interface{} 25 | } 26 | 27 | //NewMemCache If maxItemSize is zero, the cache has no limit. 28 | //if maxItemSize is not zero, when cache's size beyond maxItemSize,start to swap 29 | func NewMemCache(maxItemSize int) *MemCache { 30 | return &MemCache{ 31 | maxItemSize: maxItemSize, 32 | cacheList: list.New(), 33 | cache: make(map[interface{}]*list.Element), 34 | } 35 | } 36 | 37 | //Status return the status of cache 38 | func (c *MemCache) Status() *CacheStatus { 39 | c.mutex.RLock() 40 | defer c.mutex.RUnlock() 41 | return &CacheStatus{ 42 | MaxItemSize: c.maxItemSize, 43 | CurrentSize: c.cacheList.Len(), 44 | Gets: c.gets.Get(), 45 | Hits: c.hits.Get(), 46 | } 47 | } 48 | 49 | //Get value with key 50 | func (c *MemCache) Get(key string) (interface{}, bool) { 51 | c.mutex.RLock() 52 | defer c.mutex.RUnlock() 53 | c.gets.Add(1) 54 | if ele, hit := c.cache[key]; hit { 55 | c.hits.Add(1) 56 | c.cacheList.MoveToFront(ele) 57 | return ele.Value.(*entry).value, true 58 | } 59 | return nil, false 60 | } 61 | 62 | //Set a value with key 63 | func (c *MemCache) Set(key string, value interface{}) { 64 | c.mutex.Lock() 65 | defer c.mutex.Unlock() 66 | if c.cache == nil { 67 | c.cache = make(map[interface{}]*list.Element) 68 | c.cacheList = list.New() 69 | } 70 | 71 | if ele, ok := c.cache[key]; ok { 72 | c.cacheList.MoveToFront(ele) 73 | ele.Value.(*entry).value = value 74 | return 75 | } 76 | 77 | ele := c.cacheList.PushFront(&entry{key: key, value: value}) 78 | c.cache[key] = ele 79 | if c.maxItemSize != 0 && c.cacheList.Len() > c.maxItemSize { 80 | c.RemoveOldest() 81 | } 82 | } 83 | 84 | //Delete delete the key 85 | func (c *MemCache) Delete(key string) { 86 | c.mutex.Lock() 87 | defer c.mutex.Unlock() 88 | if c.cache == nil { 89 | return 90 | } 91 | if ele, ok := c.cache[key]; ok { 92 | c.cacheList.Remove(ele) 93 | key := ele.Value.(*entry).key 94 | delete(c.cache, key) 95 | return 96 | } 97 | } 98 | 99 | //RemoveOldest remove the oldest key 100 | func (c *MemCache) RemoveOldest() { 101 | if c.cache == nil { 102 | return 103 | } 104 | ele := c.cacheList.Back() 105 | if ele != nil { 106 | c.cacheList.Remove(ele) 107 | key := ele.Value.(*entry).key 108 | delete(c.cache, key) 109 | } 110 | } 111 | 112 | // Add atomically adds n to i. 113 | func (i *AtomicInt) Add(n int64) { 114 | atomic.AddInt64((*int64)(i), n) 115 | } 116 | 117 | // Get atomically gets the value of i. 118 | func (i *AtomicInt) Get() int64 { 119 | return atomic.LoadInt64((*int64)(i)) 120 | } 121 | -------------------------------------------------------------------------------- /memcache_test.go: -------------------------------------------------------------------------------- 1 | package cache 2 | 3 | import ( 4 | "testing" 5 | ) 6 | 7 | type simpleStruct struct { 8 | int 9 | string 10 | } 11 | 12 | type complexStruct struct { 13 | int 14 | simpleStruct 15 | } 16 | 17 | var getTests = []struct { 18 | name string 19 | keyToAdd string 20 | keyToGet string 21 | expectedOk bool 22 | }{ 23 | {"string_hit", "myKey", "myKey", true}, 24 | {"string_miss", "myKey", "nonsense", false}, 25 | } 26 | 27 | func TestSet(t *testing.T) { 28 | var cache Cache 29 | cache = NewMemCache(0) 30 | values := []string{"test1", "test2", "test3"} 31 | key := "key1" 32 | for _, v := range values { 33 | cache.Set(key, v) 34 | val, ok := cache.Get(key) 35 | if !ok { 36 | t.Fatalf("expect key:%v ,value:%v", key, v) 37 | } else if ok && val != v { 38 | t.Fatalf("expect value:%v, get value:%v", key, v, val) 39 | } 40 | t.Logf("value:%v ", val) 41 | } 42 | } 43 | 44 | func TestGet(t *testing.T) { 45 | var cache Cache 46 | cache = NewMemCache(0) 47 | for _, tt := range getTests { 48 | cache.Set(tt.keyToAdd, 1234) 49 | val, ok := cache.Get(tt.keyToGet) 50 | 51 | if ok != tt.expectedOk { 52 | t.Fatalf("%s: val:%v cache hit = %v; want %v", tt.name, val, ok, !ok) 53 | } else if ok && val != 1234 { 54 | t.Fatalf("%s expected get to return 1234 but got %v", tt.name, val) 55 | } 56 | 57 | } 58 | } 59 | 60 | func TestDelete(t *testing.T) { 61 | var cache Cache 62 | cache = NewMemCache(0) 63 | cache.Set("myKey", 1234) 64 | if val, ok := cache.Get("myKey"); !ok { 65 | t.Fatal("TestRemove returned no match") 66 | } else if val != 1234 { 67 | t.Fatalf("TestRemove failed. Expected %d, got %v", 1234, val) 68 | } 69 | 70 | cache.Delete("myKey") 71 | if _, ok := cache.Get("myKey"); ok { 72 | t.Fatal("TestRemove returned a removed item") 73 | } 74 | } 75 | 76 | func TestStatus(t *testing.T) { 77 | 78 | keys := []string{"1", "2", "3", "4", "5"} 79 | 80 | var gets int64 81 | var hits int64 82 | var maxSize int 83 | var currentSize int 84 | maxSize = 20 85 | var cache Cache 86 | cache = NewMemCache(maxSize) 87 | //keys := []string{"1", "2", "3", "4", "5"} 88 | for _, key := range keys { 89 | cache.Set(key, 1234) 90 | currentSize++ 91 | } 92 | 93 | newKeys := []string{"1", "2", "3", "4", "5", "6", "7", "8", "9", "10"} 94 | 95 | for _, newKey := range newKeys { 96 | _, ok := cache.Get(newKey) 97 | if ok == true { 98 | hits++ 99 | } 100 | gets++ 101 | } 102 | t.Logf("gets:%v, hits:%v, maxSize:%v, currentSize:%v", gets, hits, maxSize, currentSize) 103 | status := cache.Status() 104 | if status.CurrentSize != currentSize || status.MaxItemSize != maxSize || 105 | status.Gets != gets || status.Hits != hits { 106 | t.Fatalf("get status maxSize:%v, currentSize:%v, nget:%v, nhit:%v", 107 | status.MaxItemSize, status.CurrentSize, status.Gets, status.Hits) 108 | } 109 | 110 | } 111 | 112 | func TestLRU(t *testing.T) { 113 | keys := []string{"1", "2", "3", "4", "2", "1", "3", "5", "6", "5", "6"} 114 | maxSize := 3 115 | var cache Cache 116 | cache = NewMemCache(maxSize) 117 | for i, key := range keys { 118 | cache.Set(key, 1234) 119 | if i == 3 { 120 | status := cache.Status() 121 | if status.CurrentSize != maxSize { 122 | t.Fatalf("expected maxSize %v,currentSize:%v", maxSize, status.CurrentSize) 123 | } 124 | _, ok1 := cache.Get("2") 125 | _, ok2 := cache.Get("3") 126 | if !(ok1 && ok2) { 127 | t.Fatalf("expected remains key 2:%v,3:%v", ok1, ok2) 128 | } 129 | } 130 | 131 | if i == 5 { 132 | _, ok1 := cache.Get("1") 133 | _, ok2 := cache.Get("2") 134 | _, ok3 := cache.Get("3") 135 | 136 | if !(ok1 && ok2 && ok3) { 137 | t.Fatalf("expected remains key 1:%v 2:%v,3:%v", ok1, ok2, ok3) 138 | } 139 | } 140 | } 141 | 142 | status := cache.Status() 143 | if status.CurrentSize != maxSize { 144 | t.Fatalf("expected maxSize %v,currentSize:%v", maxSize, status.CurrentSize) 145 | } 146 | 147 | _, ok1 := cache.Get("3") 148 | _, ok2 := cache.Get("5") 149 | _, ok3 := cache.Get("6") 150 | if !(ok1 && ok2 && ok3) { 151 | t.Fatalf("expected remains key 3:%v,5:%v, 6:%v", ok1, ok2, ok3) 152 | } 153 | } 154 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. 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